This invention relates to the distribution of liquid in liquid-fluid contact towers wherein liquid and fluid are desired to be intimately mixed, and wherein at least part of the liquid to be mixed is fed to the tower from a site which is located external to the tower interior.
The invention is particularly useful where very small amounts of liquid fed from an external source need to be very uniformly distributed at the same level in the tower. An example of this is the feeding of reflux liquid to a distillation tower.
Liquid distributors and redistributors are well known in several arts of manufacture. They are both used to disperse a liquid uniformly in process towers. Distributors are used when the liquid to be distributed is fed to the distributor from an outside source. Redistributors are used when the liquid source is internal to the tower, e.g., collecting and redistributing liquid which is flowing downwardly through a packed tower before it becomes unacceptably non-uniformly distributed. Such maldistribution often results from the liquid forming and following channels through the column packing or results from the liquid adhering to the tower wall.
The present invention is directed toward distributors as opposed to redistributors. However, the present invention certainly could be, and likely would often be, used in the same tower with redistributors.
The principal purpose for distributors, of course, is distribute the liquid fed to them as uniformly as possible across a given horizontally oriented, imaginary, cross-sectional area of the tower. Several limiting factors prevent this distribution from being uniformly perfect. One of these factors is that uniformly perfect liquid distribution would require the distributor to have an infinite number of distribution points. This, of course, is impossible. In fact, most distributors have no more than about 3 to about 7 distribution points per square foot of tower section.
Another limiting factor is that the distribution points are often restricted in the sites in which they can be located. This results from the requirement that the distributors have sufficient open space in them to allow fluids such as vapors to pass freely up or down through them while the distributor points are still spaced from one another in a substantially uniform pattern.
Yet another significant limiting factor in having commercially available distributors distribute their liquid uniformly across a section of a tower is the problem of the tower changing position after the distributor is installed. These commercially available distributors depend upon all of their distribution points being at exactly the same height within the tower. Their distribution is very sensitive to variations in heights between the distribution points. Thus even if one of these commercially available distributors is perfectly designed, is perfectly made, and is perfectly installed within the tower, its liquid distribution will deviate far from the desired uniform distribution by a slight tilting movement of the tower. Such movement often occurs as the tower foundation settles.
The present invention significantly reduces the problems posed by these and other limiting factors.